1. Field of the Invention
The invention relates to measuring devices and methods and is directed more particularly to measurement of parameters necessary for guidance systems of torpedoes, acoustic targets, and other generally cylindrically-shaped water-borne missiles/vehicles.
2. Description of the Prior Art
For the operation of guidance systems for cylindrically shaped vehicles, such as torpedoes, acoustic targets, and other water-borne vehicles, it is necessary that certain fundamental parameters of the vehicle be known and incorporated in the data base of the guidance system. Such parameters include those directed to the "balance" of the vehicle, i.e., weight, lengthwise center of gravity, righting moment, and static heel.
Traditionally, the weight of such a vehicle has been determined by suspending the vehicle by cable from a load cell. In view of the length and weight of such vehicles, it usually is the case that heavy equipment is required, such as a tall crane from which to suspend the load cell, and thereunder, the vehicle. Once suspended in place, the weight of the vehicle is indicated by the load cell.
To determine the length-wise center of gravity, it has been customary to loop a cable around the vehicle such that the vehicle is suspended and supported in a generally horizontal position by the loop. When the vehicle teeters downwardly toward either end, the position of the cable loop on the vehicle is adjusted toward that downwardly teetering end and through trial-and-error a cable position is attained at which the vehicle is suspended in an essentially horizontal position, the position of the cable on the vehicle indicating the lengthwise center of gravity of the vehicle. Again, suspending a vehicle, such as a torpedo, and raising and lowering the vehicle so as to adjust the position of the cable thereon, often a number of times before hitting upon the point at which the vehicle is suspended in length-wise equilibrium, requires heavy equipment, a crew of people, and space in which to maneuver the equipment and the vehicle.
In accordance with the prior art, righting moment is determined by suspending two endless cables from pulleys, respectively. In the lower bends of the cable is placed the vehicle, a first cable supporting a forward portion of the vehicle and a second cable supporting an after portion of the vehicle. The vehicle is then rotated 90.degree. and a notation is made as to the force required to rotate the vehicle, the force being known as the "pull-around". The righting moment is then computed by multiplying the radius of the vehicle by the "pull-around".
Upon completion of the righting moment measurement, the vehicle is released from its turned position, whereupon the vehicle seeks return to its position of equilibrium. The difference in degrees between the equilibrium position of the vehicle and the designed upright position of the vehicle, that is, a selected position, is the static heel of the vehicle. Given the size and weight of torpedoes, and the like, righting moment and static heel measurements have traditionally required heavy equipment, a crew of substantial numbers, and space in which to operate the heavy equipment and the large crew.
Accordingly, it would be most beneficial to have a device and methods capable of effecting the above-described measurements under essentially laboratory conditions, such that continuing use of cranes and other heavy-equipment, large crews, and expansive space is not required and trial and error steps are obviated.